Título del libro: Groundwatercontaminant And Resource Management.
Título del capítulo: Study of Unsaturated Soils by Coupled Numerical Analyses of Water Flow-Slope Stability
NORMA PATRICIA LOPEZ ACOSTA;
Autores externos:
Idioma:
Inglés
Año de publicación:
2016
Palabras clave:
water flow; unsaturated soils; numerical analysis; coupled water flow-slope stability analysis; soil-water characteristic curve; hydraulic conductivity function
Resumen:
The geotechnical engineering, among the problems related to water flow, is specifically interested in soil and water that it contains, and also on the movement of water through their pores, in addition to the laws governing this phenomenon. A very important subject is to quantify the retention and filtration of water within the soil structure; however, the emphasis should be not only on how much water flows through the soil but also on the state of pore water pressures because this pressure, either positive or negative, has a direct influence on the stress state and changes in volume of soil. Several publications address the issue of water flow in saturated state; however, only some of them consider the flow under unsaturated conditions. In this chapter, the main emphasis is focused on the study of water flow in unsaturated soils. Initially, the basic concepts and the main equations applicable to the study of water flow in unsaturated media are defined. Then, fitting and estimation models of soil hydraulic functions (soil-water characteristic curve and hydraulic conductivity function) necessary to solve this type of problems are discussed. The importance of considering calculations in the unsaturated zone of the flow region is demonstrated by the analysis of a tailings dam. It is explained how to perform two-dimensional (2D) and three-dimensional (3D) numerical analysis of water flow by finite element method (FEM) under steady and transient-state conditions, whose results are evaluated and coupled to study the stability of the structure assuming the phi-b linear model for unsaturated soils. Special attention to the analysis of the variations obtained in 2D and 3D models constructed with extrusions and rough topography of the site is given. Finally, important recommendations for engineering practice according to the results obtained are issued. Some concluding remarks and recommendations of the analyses presented in this chapter are as follows: The mathematical models for estimating soil-water characteristic curve and hydraulic conductivity function are an important tool when laboratory test results are not available because of the high costs of these tests or the requirements of specialized equipment and personnel to perform them. 3D models have important advantages over 2D models because they can include irregular geometries of the structure under study, topographical configuration of soil, unsaturated flow conditions, more realistic boundary conditions representing the environment, among others. To get more representative numerical analyses, the unsaturated soil theory should be considered for all those situations where the material is in this state. In this chapter, it is demonstrated that the considerations exposed for modelling, estimation, and fitting of hydraulic functions of soil provide the necessary elements to carry out these analyses in a simple way. Computer programs facilitate the study of transient-state flow and unsaturated soil condition, whose analytical solutions are generally complicated and laborious.
Entidades citadas de la UNAM:
ISBN:
9789535124665
Editorial:
InTech
